Process of making salt cake and sulfuric acid from niter cake



UNITED STATES PATENT curios.

WILLIAM J. KEE, OF METUCHEN,

CORPORATION. OF NEW YORK.

NEW JERSEY. ASSIGNOR TO THE KALBFLEISCH N. Y., A CORIOBATION OF NEW YORK.

PROCESS OF MAKING- SALT CAKE AND SULFURIC ACID FROM NITEB CAKE.

1,313,192- 20 Drawing.

, clare that the following isa full, clear, and

charge were made 1 p entirely of heating the same to a o!" SllbdlV'iSlOH, out "it IS difllcnlt to produce a homogeneous mixexact description themof.

t. This invention relates to the conversion of niter'cekehiuto sodium sulfate (salt cake) and acid and. it pertuinscspecially to. a prooossoidwnt'osiiig niter cake by iigh tmnperatnrc.

'-.-.--It, -ihas heretofore been proposed, when convectin nitcr cake into salt cake and sul furic ucitfM'ith the aid of heat, to mix the nitcr cake before 't is heated with an equal weight' oflsilicaior ther material which will serve to prevent the mass from becoming liquid at the temperature at which the n'iler cake-giresgfl sulfur tr oxid. Such Procedure,

howevms'mnmils th following disadvtm tages: The materials before mixing must be brought to,-the. ropcr degree of fineness even when this is done tore. Th1 yieldi'rom a given number of furnaces is only about 507., of that obtained when-th liter cake is heated alone. due to the fact that the charge for each furnace, when a mixture is used, contains only half the niter cake which could he used if the niter cukc. Finally' there isugreat waste of heat dueto the necessity of heating a grrnt mass of inert material to at high temperature.

In working with 'niter cake without atlmixtures, on the other hand, the chief disadvantages are the action of the molten mass on the walls of the furnace, and. the

difiiculty in removing the snlt coke residue which tends to form a,

hard mass on solidi} ficntion; It is the removal of the salt cake which has given the most trouble, the action of the molten mass on the refractory linings which are now commonly used, being reintively unimportant.

One object 01" my invention is to (llSpUllSQ. with inert. admin! ores such as silica and avoid the diliicultics and loss in cilic'wncy cutailed there-by. Y V Another object of the invention is to iacilitato the removal of the salt cake residue from the furnace at the end of the process.

Specificdtlon of Letters Patent.

Patented Aug. 12, 1919.

In carrying out the process in accordance with my invention the ordinary'niter cake (NaHSO without other materials being mixed therewith, is u'uiintained at, a tempcruturc corresponding to, or somewhat above, the melting point of salt cake. When the evolution of sulfur trioxid is about completed there is added to the molten mass 9. small proportion, for instance 540%, of solid non-combustible material such as niter colic or salt cake, either of which may be retherein would be melted a in short time. Nitcr cake an saltl cake are used in preference to other materials as cooling agents since they do not form extruneous substances in the salt cake residue. The rocess may be illustrated in greater detail y the following example:

One thousand arts of niter cake are charged into a suitable reverberatory furnuco maintained at a constant temperature corresponding to the melting int of salt cake or a little above. The call: is quickly melted and decomposes uite rapidly into salt cake and sulfuric aci the reaction a parent-1y going in acwrdenoc with the i0 lowing equations:

When the evolution of sulfur trioxid has practically ceased, indicating that the reaction has been practically brought to complction, that is when there is only 1% or less of nitcr cake which remains undecomposed, the molten mass in the furnace will consist of about 600 parts of salt cake. At this time and while the molten mass is being well stirred; there are added to it from 30 to 60 parts of niter cake or saltcake. The niter cake has a little greater freezing action than an equal weight of salt cake since it absorbs heat in decomposing into water, sulfur triett oxid and sodium sulfate. Within a very short time after the niter cake or salt cake has been added, the molten mixture solidifies into a friable, lumpy inass which is easily withdrawn from the furnaces with a hoe or similar instrument. This withdrawal however must be accomplished without delay, since if the mass again becomes melted it is diliicult to remove,

It will be evident from the above description that the new process offers many advantages over those heretofore known. By causing inci ient freezing of the molten salt cake by ad in thereto solid uiter cake or solid salt cake in small amount, the cooling ofthe furnace at the end of each operation to permit the salt cake to solidify and to be removed is rendered unnecessary.

It will be understood that various changes in detail ma be made in the above described processwi out departing from the scope of m invention. 4

I c aim: a 1. The process of producing salt cake and sulfuric acid from niter cake which cdmprises melting niqter calm in a suitable fur- MQ a ining the Inter cake at such a. temperature that it becomes'conveitedrmtq molten salt cake, with evolution a of sulfur trioxid, addin a suflicien-t proportion of a suifateof s ium in the sohd condition to the continually stirred molten mass when the reaction is substantiallv completed to cause the molten mass to solidify,aml then withdrawing the solid salt, cake from the furnace.

2. The process of producin cake and sulfuric acid from niter ea c which oomprisas melting niter cake in a, suitable fornace, maintaining the niter cal-re at about the oint of salt cake until it becomes into molten salt cake with evolution of sulfur t-rioxid, adding from about melting 5 to 10% based on the weight of molten,

salt cake of a. sulfate of sodium in the/- solid I a I g F i i A condition to the continually stirred molten .mass when the reaction is substantially ofsult ea c, the steps which-compriseadding asuflicient amount of'solid non-combustible material to the molten salt cake residue, while stirring, to cause solidification thereof, and withdrawing the solidified material from the furnace" bforo the salt cake'be comes mmelted. v

4. In the process of producing salt cake and sulfuric acid fro miter cake by de- A composing the latter in a suitable furnace u-t'a temperature above the melting point of salt cake, the steps which comprise adding a suflicient auiount eta-sulfate of sodium in the solid condition to the molten saltcake residue, while, stirrin to cause solidification thereof, and with mwing the'solidificd -1nater1al from the furnace before the salt cake lfccoges remeltedi d l a m; t in sat P hitili tiakebjf deconiposing the latter in a suitable furnace at a.

temperature above the melting point, of salt cake, the steps which comprise adding to the molten salt cake residue, while stirring, from about 5 to 10% of a. sulfate of sodium in the solid condition, lmscd on the weight of said molten salt cake. to causothc latter to' solid ify. and then withdrawin the resulting easily disintegrated sol id sa t cake from the furnace. v

In testil'nony that I claim the foregoing I have hereunto set my ha nd.

WILLIAM J. KEE.

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